1. Field of the Invention
The present invention relates to a mass-production packaging means for an organic electroluminescent display (OLED) and a process therefor.
2. Description of the Related Art
Since an organic small molecule electroluminescent device was proposed by US Kodak company in Appl, Phys. Lett., Vol. 5, p. 914 (1987) and a polymer material was successfully applied to the electroluminescent device as published in Nature, Vol. 347, p. 539 (1990) by Cambridge University, Britain, the electroluminescent device has been proved to be put into practice. Therefore, many attempts of related research and development have been proposed in many countries.
The organic electroluminescent device has advantages such as self-luminescence, board visual angle (up to 160 degrees), high feedback speed, low driving voltage, full color, etc., that it is considered a new-generation plane display technology. Currently, the organic electroluminescent device is approaching the stage of actual usage and is expected to be the material for a new-generation color plane display. The high level application for the plane luminescent device aims at full color plane display devices, such as small display panels, out-door display panels, and computer and television monitors. However, since the development of this new technology started later than other displays, the new technology still can not be put into practice. Currently, only Japan Pioneer company produces small-size related products. This reveals that the commercialization of the organic electroluminescent display needs to overcome a lot of obstacles, especially in mass production.
At present, most of the attempts of research and development of the organic electroluminescent device focus on the structure of the device and material therefor. Few packaging technologies are known in the art. A summary of the related prior art is as follows:                1. U.S. Pat. No. 5,882,761 to Pioneer discloses a packaging method for an organic electroluminescent device, and a hygroscopic material. However, no description about a mass-production method is provided.        2. U.S. Pat. No. 6,049,167 to TDK discloses a packaging method for an organic electroluminescent device. However, a water-absorptive material is not included. The equipment for the package is batch type equipment, which is suitable only for a laboratory, not for mass production.        3. U.S. Pat. No. 5,958,778 to IBM discloses a packaging method for an organic electroluminescent device, which is characterized by a multilayer protective film and glass or metal used to package the device. However, mass-production of a multilayer film is considerably difficult. Moreover, the adhesion between different materials is also hard to imrpove. Therefore, the IBM method is not useful in a mass-production packaging method.        4. U.S. Pat. No. 5,962,962 to Idemitsu discloses a packaging method for an organic electroluminescent device, which is characterized in that non-active liquid having a hygroscopic material is used to protect the device. However, all of the materials used must be demoisturized to ensure the performance thereof. Therefore, the Idemitsu method is not suitable in a mass-production packaging.        5. U.S. Pat. No. 5,990,615 to NEC discloses a packaging method of an organic electroluminescent device, which is characterized over Pioneer and Idemitsu in that a protective layer is additionally provided on the device. However, similar disadvantages as that in the Pioneer and Idemitsu methods still exist.        
As discussed above, in the prior packaging methods, no teaching shows how to carry out mass production is disclosed. Moreover, the technologies disclosed are not useful in mass production. The present invention aims to overcome the obstacles in the prior art and provide a novel mass-production packaging means and a process therefor.